“Republicans are lashing out at Sen. Reid because he’s been speaking out about the Republicans’ blind obedience to the shadowy billionaire Koch brothers as they work together to rig the system to benefit the top 1 percent,” he said. “Republicans rushing to defend the billionaire Koch brothers is just further evidence that when the Koch brothers say jump, Republicans ask, ‘how high?’ ”

During an appearance on "Fox and Friends," Priebus accused Reid of behaving unethically.

“He doesn't use a separate website and a separate Twitter account for these attacks. So he's clearly using staff, taxpayer money, resources, a website, and computer equipment to launch partisan campaign attacks on the taxpayers' money,” Priebus said.

“These are things that most cases, believe it or not, in Washington that senators have a different website and a different Twitter account to launch these partisan attacks.”

Democrats have made the Koch brothers a prominent part of their midterm election strategy, repeatedly attacking the brothers for spending millions of dollars to help Republicans win back the Senate.

Republicans have decried the attacks as an attempt to silence speech, and note that the liberal donor Tom Steyer has vowed to spend tens of millions dollars this election cycle backing candidates in favor of action on climate change. That spending is likely to favor Democrats by a wide margin.